/* ============================================================
   GLASSGRID — POST CARD COMPONENT
   
   ⚠️  STRUCTURE IS FIXED. Do not modify class names.
   ⚠️  All visual changes through tokens/components.css only.
   ⚠️  Schema-validated post objects only. No raw HTML.
   ============================================================ */

'use strict';

import { store, showToast } from '../lib/store.js';
import { api } from '../lib/api.js';

/**
 * Render a post card element.
 * @param {Object} post  - Schema.Post validated object
 * @param {Object} user  - Schema.User for the post author
 * @returns {HTMLElement}
 */
export function PostCard(post, user) {
  const liked  = store.get('liked')?.[post.id]  ?? false;
  const saved  = store.get('saved')?.[post.id]  ?? false;
  const config = store.get('config') ?? {};
  const features = store.get('features') ?? {};

  const el = document.createElement('article');
  el.className = 'post-card glass animate-fadeInUp';
  el.dataset.postId = post.id;
  el.setAttribute('role', 'article');

  el.innerHTML = `
    <!-- PostCard__header -->
    <div class="post-card__header">
      <div class="avatar avatar--md ${user.hasStory ? 'avatar--ring gradient-border' : ''}">
        <img
          src="${escHtml(user.avatarUrl || '/assets/images/default-avatar.png')}"
          alt="${escHtml(user.displayName)}'s avatar"
          class="avatar__img"
          loading="lazy"
          width="40" height="40"
        />
      </div>
      <div style="flex:1;min-width:0;">
        <div class="post-card__username">${escHtml(user.displayName)}</div>
        <div class="post-card__handle">
          @${escHtml(user.username)}
          ${post.location ? `<span class="post-card__handle"> · ${escHtml(post.location)}</span>` : ''}
        </div>
      </div>
      <span class="post-card__timestamp">${formatRelativeTime(post.createdAt)}</span>
      <button class="post-card__more-btn" aria-label="More options" data-action="more">
        ${IconMore()}
      </button>
    </div>

    <!-- PostCard__media -->
    <div class="post-card__media post-card__media--${post.aspectRatio}">
      <img
        src="${escHtml(post.mediaUrl)}"
        alt="${escHtml(post.altText || post.caption || 'Post image')}"
        loading="lazy"
        decoding="async"
      />
    </div>

    <!-- PostCard__actions -->
    <div class="post-card__actions" ${!features.likes && !features.comments ? 'style="display:none"' : ''}>
      ${features.likes ? `
        <button
          class="post-card__like-btn ${liked ? 'liked' : ''}"
          data-action="like"
          aria-label="${liked ? 'Unlike post' : 'Like post'}"
          aria-pressed="${liked}"
        >
          ${liked ? IconHeartFilled() : IconHeart()}
          <span class="post-card__like-count">${formatCount(post.likeCount)}</span>
        </button>
      ` : ''}

      ${features.comments ? `
        <button class="post-card__comment-btn" data-action="comment" aria-label="Comment on post">
          ${IconComment()}
          <span>${formatCount(post.commentCount)}</span>
        </button>
      ` : ''}

      ${features.saves ? `
        <button
          class="post-card__save-btn ${saved ? 'saved' : ''}"
          data-action="save"
          aria-label="${saved ? 'Unsave post' : 'Save post'}"
        >
          ${saved ? IconBookmarkFilled() : IconBookmark()}
        </button>
      ` : ''}
    </div>

    <!-- PostCard__caption -->
    ${post.caption ? `
      <div class="post-card__caption">
        <p class="post-card__caption-text">
          <span class="post-card__caption-username">${escHtml(user.username)}</span>${escHtml(post.caption)}
        </p>
      </div>
    ` : ''}

    <!-- PostCard__comments-preview -->
    ${post.commentCount > 0 && features.comments ? `
      <div class="post-card__comments-preview">
        <button class="post-card__view-comments" data-action="comment">
          View all ${formatCount(post.commentCount)} comments
        </button>
      </div>
    ` : ''}
  `;

  // ── Event Delegation ──
  el.addEventListener('click', async (e) => {
    const btn = e.target.closest('[data-action]');
    if (!btn) return;

    switch (btn.dataset.action) {
      case 'like':    await handleLike(el, post); break;
      case 'comment': handleComment(post.id);     break;
      case 'save':    await handleSave(el, post); break;
      case 'more':    handleMore(post, user);     break;
    }
  });

  return el;
}

// ── Handlers ──

async function handleLike(el, post) {
  const liked   = store.get('liked') ?? {};
  const isLiked = liked[post.id] ?? false;
  const likeBtn = el.querySelector('[data-action="like"]');
  const countEl = el.querySelector('.post-card__like-count');

  // Optimistic update
  const newLiked = !isLiked;
  store.update('liked', prev => ({ ...prev, [post.id]: newLiked }));
  likeBtn?.classList.toggle('liked', newLiked);
  likeBtn?.setAttribute('aria-pressed', String(newLiked));
  if (likeBtn) likeBtn.innerHTML = (newLiked ? IconHeartFilled() : IconHeart()) +
    `<span class="post-card__like-count">${formatCount(post.likeCount + (newLiked ? 1 : -1))}</span>`;

  if (newLiked) likeBtn?.classList.add('animate-heartPop');
  setTimeout(() => likeBtn?.classList.remove('animate-heartPop'), 600);

  try {
    if (newLiked) await api.likePost(post.id);
    else          await api.unlikePost(post.id);
  } catch {
    // Revert on failure
    store.update('liked', prev => ({ ...prev, [post.id]: isLiked }));
    likeBtn?.classList.toggle('liked', isLiked);
    showToast('Could not update like. Try again.');
  }
}

async function handleSave(el, post) {
  const saved   = store.get('saved') ?? {};
  const isSaved = saved[post.id] ?? false;
  const saveBtn = el.querySelector('[data-action="save"]');

  store.update('saved', prev => ({ ...prev, [post.id]: !isSaved }));
  saveBtn?.classList.toggle('saved', !isSaved);
  showToast(!isSaved ? 'Saved to collection' : 'Removed from collection');
}

function handleComment(postId) {
  const ui = store.get('ui');
  store.set('ui', { ...ui, commentModal: postId });
}

function handleMore(post, user) {
  document.dispatchEvent(new CustomEvent('gg:post:more', { detail: { post, user } }));
}

// ── Helpers ──

function escHtml(str) {
  if (!str) return '';
  return String(str)
    .replace(/&/g, '&amp;')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#39;');
}

function formatRelativeTime(timestamp) {
  const diff = (Date.now() - new Date(timestamp)) / 1000;
  if (diff < 60)    return 'now';
  if (diff < 3600)  return `${Math.floor(diff/60)}m`;
  if (diff < 86400) return `${Math.floor(diff/3600)}h`;
  if (diff < 604800)return `${Math.floor(diff/86400)}d`;
  return new Date(timestamp).toLocaleDateString();
}

function formatCount(n = 0) {
  if (n >= 1_000_000) return `${(n/1_000_000).toFixed(1)}M`;
  if (n >= 1_000)     return `${(n/1_000).toFixed(1)}K`;
  return String(n);
}

// ── SVG Icons ──
function IconHeart()         { return `<svg width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M20.84 4.61a5.5 5.5 0 0 0-7.78 0L12 5.67l-1.06-1.06a5.5 5.5 0 0 0-7.78 7.78l1.06 1.06L12 21.23l7.78-7.78 1.06-1.06a5.5 5.5 0 0 0 0-7.78z"/></svg>`; }
function IconHeartFilled()   { return `<svg width="22" height="22" viewBox="0 0 24 24" fill="currentColor" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M20.84 4.61a5.5 5.5 0 0 0-7.78 0L12 5.67l-1.06-1.06a5.5 5.5 0 0 0-7.78 7.78l1.06 1.06L12 21.23l7.78-7.78 1.06-1.06a5.5 5.5 0 0 0 0-7.78z"/></svg>`; }
function IconComment()       { return `<svg width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M21 15a2 2 0 0 1-2 2H7l-4 4V5a2 2 0 0 1 2-2h14a2 2 0 0 1 2 2z"/></svg>`; }
function IconBookmark()      { return `<svg width="22" height="22" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M19 21l-7-5-7 5V5a2 2 0 0 1 2-2h10a2 2 0 0 1 2 2z"/></svg>`; }
function IconBookmarkFilled(){ return `<svg width="22" height="22" viewBox="0 0 24 24" fill="currentColor" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M19 21l-7-5-7 5V5a2 2 0 0 1 2-2h10a2 2 0 0 1 2 2z"/></svg>`; }
function IconMore()          { return `<svg width="20" height="20" viewBox="0 0 24 24" fill="currentColor"><circle cx="12" cy="5" r="1.5"/><circle cx="12" cy="12" r="1.5"/><circle cx="12" cy="19" r="1.5"/></svg>`; }